The objective of this study was to examine the impact of low birth weight and preterm birth on a toddler's inattention and development, including cognitive, language, motor, social-emotional and adaptive behaviors. A total of 105 toddlers enrolled for the study; they were divided into four groups: 40 full-term and normal birth weight (NBW, birth weight greater than 2500 g) toddlers, 24 moderate birth weight (MLBW, birth weight between 2499 and 1500 g) toddlers, 20 very to extremely low birth weight (V-ELBW, 12 between 1000 and 1499 g and 8 lower than 1000 g) toddlers, and 21 term toddlers who were recruited from a clinic of developmental delay as the developmental delay at risk (DDR) group. The Bayley Scales of Infant and Toddler Development-Third Edition (BSID-III) and Disruptive Behavior Rating Scale-Toddler were used. The findings were as follows: (1) DDR group performed worst in BSID-III; (2) although there were no statistical differences among the NBW, MLBW, and V-ELBW groups in BSID-III, the lower the birth weight, the lower the average performance, especially in language, adaptive social behavior, and adaptive practical behavior; and (3) comparing the inattention score, the DDR group was the poorest, normal and V-ELBW groups were the best, and MLBW group was in the middle. In conclusion, low birth weight and preterm delivery affected children's inattention and development of language, adaptive social behavior, and adaptive practical behavior.